Flexible cables are used, e.g., as electric power lines for moving machines, in which the cables can be wound on drums or dragged. They are used at surface mining sites and underground mining sites.
In the design of cables of this type, it is necessary to optimize the expansion behavior of the conductors for small bend radii and to provide the cable with sufficient tensile strength.
The German journal “Elektrodienst”, 1983, No. 1, pp. 26–27, describes an elevator control cable, in which the cores are stranded around a supporting member to form a cable core, and the cable core is surrounded by a plastic sheath. The previously known cable is distinguished by a cable structure in which five cores are stranded around a core with high tensile strength to form a bundle, and six of these bundles are then arranged with a short length of lay around the supporting member, which is designed as a torsion-free steel cable. The advantages of this design are:                high flexural fatigue strength,        high flexibility, and        absolute stability of the core construction        